C Loopback Tests
91
Appendix C: Loopback Tests
Introduction
Each time you turn on your modem, it performs an automatic self-test to ensure
proper operation. Your modem also has three diagnostic tests: local analog loop-
back, remote digital loopback, and local digital loopback. These ITU-T V.54 loop-
back tests isolate telephone circuit and transmission problems.
In a loopback test, data from your computer loops through the circuits of your mo-
dem and/or a remote modem before it appears on your monitor. When the loop has
been completed, the data on your PC’s monitor should match the original data.
The local analog loopback test allows you to verify that the modem’s transmitter
and receiver circuits are functioning properly.
The local digital loopback allows you to verify that the local computer or terminal,
the two modems, and the transmission line between them are functioning properly.
The remote digital loopback test allows you to verify that the remote computer or
terminal, the remote modem, the serial ports, the telephone line, and the local mo-
dem are functioning properly.
Note
: All loopback tests operate at all speeds except 300 bps.
Local Analog Loopback Test (V.54 Loop 3)
In this test, data from your computer or terminal is sent to your modem’s transmit-
ter, converted into analog form, looped back to the modem’s receiver, converted into
digital form, and then sent to your monitor for verification. No connection to the
phone line is required.
Computer or Terminal
Digital
Analog
AT&T1
CONNECT
UUUUUUUUUUUU
Local MultiModem
Figure C-1. Local analog loopback test.
Test procedure
1. Connect the modem to your computer. Using your communication program, set
the desired baud rate and go into terminal mode.
2. Type AT and press E
NTER
; you should get an OK message. Type AT\N and
press E
NTER
to disable error correction.
Summary of Contents for MT5600BA
Page 1: ...Model MT5600BA Model MT5600BL Data Fax Modem User Guide...
Page 7: ...Contents vii Appendix G ASCII Character Map 106 Index 107...
Page 8: ...MultiModemII User Guide viii...
Page 9: ...1 Introduction...
Page 13: ...2 Quick Start...
Page 24: ...MultiModemII User Guide 16...
Page 25: ...3 Using the Front Panel...
Page 28: ...MultiModemII User Guide 20 Trunks Limbs Branches Twigs Menu Overview...
Page 39: ...4 AT Commands S Registers Result Codes...
Page 64: ...MultiModemII User Guide 56...
Page 65: ...5 Remote Configuration...
Page 68: ...MultiModemII User Guide 60...
Page 69: ...6 Callback Security...
Page 76: ...MultiModemII User Guide 68...
Page 77: ...7 Leased Line Operation...
Page 82: ...MultiModemII User Guide 74...
Page 83: ...8 Solving Problems...
Page 91: ...Appendixes...
Page 115: ...Index...